Manufacture of hydrogen peroxide



Patented Mal-.1, 1932 UNITED STATES PATENT OFFICE ASSIGNOBSTOLG.I

: :1: w 011 mm men uoacx, o1- nr-on or nunwr-on-mnnmn, omen, w us'rmanme, or rnAnxroa'r-onmac-rum! I O! rnnoxmn Io Drawing. Application fled Inc 21, 1'8, lerlal Io. 87,8", and in Ger-any July 13, an.

The present invention relates to an improvement in the manufacture of hydrogen peroxide by cathodic reduction of oxygen, more particularly it relates to a process in 5 which the same current of oxygen or of the oxygneg-containing gas, for the wor g ofthe electrol ic cell, is used for the concentration or distillation of the h drogen peroxide solution produced in t electrolytic cell.

In the manufacture of hydrogen peroxide by cathodic reduction of oxygen a vigorous stream of oxygen or of an oxygen-containing gas is passed through the cathode space of 16 the electrolysis vessel. Since only a fraction of the same is consumed in the reduction, the oxygen or the oxygen-containing gas must be pumped back again in the technical a plication of the process. Moreover,

20 the hy rogen peroxide solutions produced by electrolysis, which are usually very dilute, must be concentrated and distilled. The pumping back and especially the concmtration of the dilute solutions involve considerable expenses.

. In accordance with the present invention the cost of concentrating is considerabl reduced, if the current of oxygen or o the oxygen-containin gas required to produce a thorough stirring in the electrolytic cell is utilized in the manner known per se forthe concentration or distillation of the hydrogen peroxide solutions produced in the electrolytic cell. This can be carried out in various ways. The concentration can be effected in the electrolysis vessel during the electrolysis by drying the oxygen or the oxygen-containing gas or at any rate taking precautions that it reaches the electrolytic cell containing less water than corresponds to the degree of saturation at the temperature of the electrolytic cell. It is however more advantageous to carry out the electrolysis and concentration and especially the distillation in separate apparatus, since in this manner a much higher average current elliciency can be attained, which may amount to 100per cent. This may likewise be carried out in various manners. It may be of advantage to maintain in the evaporation ime in order to lead it back apparatus or in parts thereof, a higher temture than in the electrol sis apparatus,

in which case the 0' gen or t e oxygen-congas is cooled fore entering the electrolytlc cell to the temperature of the latter. By working, for example, in such a manner that the temperature in an electrolytic cell amounts to 13 C. and more than C. in the evaporation apparatus (cons of a trickling tower, which can be hea and that the current of gas is cooled to 13 C. after leaving the trickling tower, the quantity of gas necessary for stirring suflices to concentrate a one per cent. hydrogen peroxmall ide solution, flowing continually from the electrolytic cell, to a 30 per cent solution. Anotherpracticable mode of working consists in keeping the temperature in the electrolysis and concentration apparatus, at least in parts thereof, substantially uniform, in which case the oxygen or oxygen-containing for example air, is dried before entermg the concentration vessel. In this manner, for example, it is possible to concentrate a certain quantity of a one percent solution produced in the electrolysis vessel to 30% y the stream of oxygen needed for its production. Finall it may be advantageous to work in suc a manner that the water evaporating in the concentration apparatus is condensed in'the suitably cooled electrolysis apparatus. With this mode of execution the constant replenishing of the cathode liquor required for continuous working becomes to arlal'ge extent automatic. It thus will be unnecessary to condense the water evaporated in the concentration apparatus in a special separating apparato the cathode ace. When it is intended to free the hygen roxide solution obtained in this process In the electrolyte by distilldtion or to purify the same in any other manner, the working is out, for example, in the following manner The dried current of oxygen is introduced into a tower and brought into contact-with an .alread concentrated solution of hydrogen peroxi e n w: a considerable hydrogen peroiide parti pressure.

The current of gas leaving the tower laden oxygen to the temperature of the electrolysis with water and hydrogen peroxide vapors apparatus before passing it into the latter. is then cooled in a condensation vessel, it In testimony whereof we havehereunto being advantageous in order to obtain a disset our hands.

5 tillate of the highest possible concentration, A OSWIN NITZSCHKE. [L 5.] 7

to condense onl part of the vapors. The ERICH NOACK. [L. 5.] gas thus partially dried by cooling is then LEO SCHLECHT. [L 5.

used again for the further concentration of a dilute solution. By repeated cooling or j 'dryingof the oxygen or the oxygen-contain- 75 ing gas in any other appropriate manner, for example, by means of active silicic acid, the production, concentration and distillation of the hydrogen peroxide solution may be carried out simultaneously in a single cycle p9 of operations. The process thus offers the possibility of producing in a very economical manner and in one process highly concentrated and pure hydrogen peroxide solutions by the cathodic 85 reduction of oxygen.

We claim: 1. In the process for the manufacture of hydrogen peroxide by cathodic reduction of 4 oxygen the step which comprises concentrato ing the hydrogen peroxide solution produced in the electrolytic cell by passing throughit the same current of oxygen which is required for the working of the electroly- .tic cell. I i 95 2. In the process for the manufacture of hydrogen peroxide by cathodic reduction of oxygen the step which comprises concentrating the hydrogen peroxide solution produced 7 in the electrolytic cellby passing through it we the same current of oxygen which is required for the working of the electrolytic cell, said concentration ordistillation step being carried out in an apparatus separate from the electrolytic cell.

3. In the process for the manufacture of hydrogen peroxide by cathodic reduction of oxygen the steps which comprise concentrating the hydrogen peroxide solution produced in the'electrolytic cell by passing through it p 10 the same current of oxygen which is required for the working of the electrolytic cell, said concentration or distillation step being carried out in an apparatus separate from the electrolytic cell, and maintaining the eva ration apparatus or parts thereof at a high r temperature than the electrolysis apparatus.

4. In the process for the manufacture of hydrogen peroxide by cathodic reduction of c oxygen the steps which comprise concentratno ing the hydrogen peroxide solution produced in the electrolytic cell by passing through it the same current of oxygen which is required for they working of the electrolytic cell, said 0 concentration or distillation step being carl2 ried out in an apparatus separate from the electrolytic cell, maintaining the evaporation J apparatus or parts thereof at a higher temperature than the electrolysis apparatus and of reducing the temperature of the current of 

